Internal mold release agents used in the production of molded polyurethane and polyurea products are known. U.S. Pat. Nos. 4,201,847 and 4,254,228 describe an internal mold release which is the reaction product of an organic polyisocyanate and an active hydrogen containing fatty acid ester.
More recently, zinc carboxylates containing from 8 to 24 carbon atoms per carboxylate group have been described (U.S. Pat. Nos. 4,519,965, 4,581,386, 4,585,803 and 4,764,537, and British Patent No. 2,101,140).
While each of these types of internal release agents has met with some success, neither is totally satisfactory for many applications. One shortcoming of all internal release agents to date, including those described above, is the inability to release from a bare metal mold, such as steel or aluminum, without first treating the internal surface of the mold with an external release agent.